<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div>哈哈</div>
    <script>

        // 1.获取元素
        const h = document.querySelector('div')
        //2.获取文本
        h.innerText = '我修改了一下'
        //第二种方法
        h.innerHTML = '<strong>我修改了一下</strong>'
    </script>
</body>

</html>